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    & Landscape supply

    How Drought Affects Turf

    Being irrigation experts, we all have a pretty firm grasp on evapotranspiration, but let's talk about it more from a physiological aspect of how it affects the turfgrass plant. Just as a refresher, evapotranspiration or ET is the total amount of water lost to the atmosphere through evaporation from the soil surface and transpiration loss from plant leaves.

    When water loss outpaces irrigation or rainfall, the plant begins to lose moisture content leading to reduced shoot growth and density, reduction in chlorophyll, and overall vigor. More extreme conditions lead to root loss, dormancy, canopy thinning, and ultimately death. 

    There are other factors that come into play as the plant begins to decline. A sparse canopy will allow sunlight to get to the soil surface encouraging weed seed germination. These weeds can grow aggressively and outcompete the turf for moisture, sunlight, nutrients, and real estate in general. Sunlight on the soil can also accelerate degradation of pre-emergent barriers leading to unhappy customers.

    Additionally, drought-stressed turf tends to become more susceptible to insect feeding, particularly grubs as well as certain diseases. Anthracnose and Ascochyta become much more of a problem when paired with droughty conditions. Some of the early symptoms to look for are leaf folding, foot printing, and uneven dew formation. These could be followed by blueish to gray discoloration and leaf roll before it starts turning tan and heading into dormancy.

    Dormancy isn’t a bad thing. In fact, it is a protective scenario where the plant will not expend further reserves to keep growth going while moisture availability is low. The crown of the plant can stay alive for 4 – 5 weeks with no water waiting for more suitable conditions to start regrowth.

    One of the more unknown facts though, is that you should still water turf dormant due to drought stress in order to keep the crown alive. The rates of water recommended are ¼ - ½ inch every 2 to 4 weeks.

    It is not advisable to water heavily in an attempt to pull the turf out of dormancy. Any bid to break dormancy with water can lead to depletion of reserves set aside for use when conditions become more hospitable. Failure to maintain some crown hydration can result in the previously mentioned death of the plant. Along with that, mowing, fertility, and weed control operations should all be suspended until the plant is actively growing again.

    Managing turf before the onset of stress consists of several facets, none more important than proper turf selection. According to Dr. Keith Karnock, the species matters. Here is his list of warm season and cool season grasses from most drought tolerant to least:

    Buffalograss, Bermudagrass, Zoysiagrass, Bahiagrass, St. Augustinegrass, Centipedegrass and cool season: Hard Fescue, Sheep Fescue, Tall Fescue, Red Fescue, Kentucky Bluegrass, Perennial Ryegrass, Annual Ryegrass, Creeping Bentgrass, and lastly Annual Bluegrass.

    Now armed with this bit of information you can make better recommendations in terms of lawn establishment particularly where irrigation is absent or climactic regions where drought is more of a chronic issue. If you have never visited the U.S. Drought Monitor website, it is a great tool. Currently, it indicates that at least 73% of the contiguous United States is abnormally dry with over 13% of the U.S. in extreme drought.

    Please feel free to contact the Ewing Technical Services Team with any questions.

    TAGS: turf solutions, Drought, Maintaining Turf, Turf Management, turf tips, Drought Stress